Keto based diet vs. Lean Gains?

I'd just like to know from the people who have tried either or both, which do you believe has more science backing it and which is better at maintaining lean mass while cutting bodyfat? I remember Arnold stating something in his book in regards to he thought that low carb diets were the best for getting definition, yet I don't think he ever did a keto type of diet. I've only done CKD, Anabolic Diet, and TKD, and they worked good for me but I love doing my HIIT cardio and I do boxing as well, and I need more energy, but would love to get rid of my bellyfat. Overall, which is more effective?